scam - how do I know that ebay asking for my licence number is not a phishing scam?

[flight-of-ducks]

There does not seem to be any way of contacting ebay.

[katistrophik]

Go to your messages in your eBay account and check there, the message will be there as well.

eBay require identification and verification so you can be switched from Paypal to Managed Payments.